// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/unicode-inl.h"
#include "src/unicode-decoder.h"
#include <stdio.h>
#include <stdlib.h>

namespace unibrow {

uint16_t Utf8Iterator::operator*()
{
    if (V8_UNLIKELY(char_ > Utf16::kMaxNonSurrogateCharCode)) {
        return trailing_ ? Utf16::TrailSurrogate(char_)
                         : Utf16::LeadSurrogate(char_);
    }

    DCHECK_EQ(trailing_, false);
    return char_;
}

Utf8Iterator& Utf8Iterator::operator++()
{
    if (V8_UNLIKELY(this->Done())) {
        char_ = Utf8::kBufferEmpty;
        return *this;
    }

    if (V8_UNLIKELY(char_ > Utf16::kMaxNonSurrogateCharCode && !trailing_)) {
        trailing_ = true;
        return *this;
    }

    trailing_ = false;
    offset_ = cursor_;

    char_ = Utf8::ValueOf(reinterpret_cast<const uint8_t*>(stream_.begin()) + cursor_,
        stream_.length() - cursor_, &cursor_);
    return *this;
}

Utf8Iterator Utf8Iterator::operator++(int)
{
    Utf8Iterator old(*this);
    ++*this;
    return old;
}

bool Utf8Iterator::Done()
{
    return offset_ == static_cast<size_t>(stream_.length());
}

void Utf8DecoderBase::Reset(uint16_t* buffer, size_t buffer_length,
    const v8::internal::Vector<const char>& stream)
{
    size_t utf16_length = 0;

    Utf8Iterator it = Utf8Iterator(stream);
    // Loop until stream is read, writing to buffer as long as buffer has space.
    while (utf16_length < buffer_length && !it.Done()) {
        *buffer++ = *it;
        ++it;
        utf16_length++;
    }
    bytes_read_ = it.Offset();
    trailing_ = it.Trailing();
    chars_written_ = utf16_length;

    // Now that writing to buffer is done, we just need to calculate utf16_length
    while (!it.Done()) {
        ++it;
        utf16_length++;
    }
    utf16_length_ = utf16_length;
}

void Utf8DecoderBase::WriteUtf16Slow(
    uint16_t* data, size_t length,
    const v8::internal::Vector<const char>& stream, size_t offset,
    bool trailing)
{
    Utf8Iterator it = Utf8Iterator(stream, offset, trailing);
    while (!it.Done()) {
        DCHECK_GT(length--, 0);
        *data++ = *it;
        ++it;
    }
}

} // namespace unibrow
